console.log('start')//1
setTimeout(() => {
  console.log('timer1')//4
  Promise.resolve().then(function () {
    console.log('promise1')//5
  })
}, 0)
setTimeout(() => {
  console.log('timer2')//6
  Promise.resolve().then(function () {
    console.log('promise2')//7
  })
}, 0)
Promise.resolve().then(function () {
  console.log('promise3')//3
})
console.log('end')//2


